Current electric appliances demonstrate a tendency to have a reduced weight and a smaller size, which leads to development of electrochemical devices, such as lithium ion secondary batteries, having a high energy density. Further, electrochemical devices such as lithium ion secondary batteries are used in more various fields, and thus are desired to have improved characteristics. In particular, improvement of battery characteristics of lithium ion secondary batteries will become a more and more important factor when the batteries are put in use for automobiles.
Lithium ion secondary batteries need to have various characteristics, such as initial capacity, rate characteristics, cycle characteristics, high-temperature storage characteristics, low-temperature characteristics, continuous charge characteristics, self-discharge characteristics, and overcharge prevention characteristics. For the purpose of improving these characteristics, methods for incorporating various additives into an electrolyte solution have been proposed.
For example, Patent Literature 1 discloses a non-aqueous electrolyte solution containing a specific unsaturated sultone as an invention intended to suppress decomposition of a solvent on a negative electrode, thereby suppressing a decrease in capacity of a battery, generation of gas, and deterioration in load characteristics of the battery during high-temperature storage.
Patent Literature 2 discloses, as an invention intended to improve the high-temperature characteristics, an electrolyte solution containing a solvent and an electrolyte salt, wherein the solvent contains a cyclic carbonate ester derivative having a halogen atom and a specific sulfur-containing compound.
Patent Literature 3 discloses, as an invention intended to improve the continuous charge characteristics, a non-aqueous electrolyte solution including a lithium salt dissolved in a non-aqueous organic solvent, wherein the non-aqueous organic solvent contains a cyclic carbonate having a fluorine substituent and/or a carbon-carbon unsaturated bond, and the non-aqueous electrolyte solution contains 0.001 to 1.5 wt % of a cyclic anhydride and 0.001 to 10 wt % of a S═O group-containing organic compound relative to the weight of the non-aqueous electrolyte solution.
Patent Literature 4 discloses, as an invention intended to improve both the storage characteristics and the cycle characteristics, a non-aqueous electrolyte solution including a lithium salt dissolved in a non-aqueous organic solvent, wherein the non-aqueous organic solvent contains a fluorine-substituted cyclic carbonate, and the non-aqueous electrolyte solution contains a diisocyanate and one or more sulfur compounds selected from the group consisting of sulfoxides, sulfites, sulfones, sulfonates, sultones, and sulfates.
Patent Literature 5 discloses, as an invention intended to improve the cycle characteristics, the electric capacity, the storage characteristics in a charged state, and other properties, a lithium secondary battery including a positive electrode, a negative electrode, and a non-aqueous electrolyte solution containing an electrolyte dissolved in a non-aqueous solvent, wherein the positive electrode is a material containing a lithium complex oxide, the negative electrode is a material containing graphite, and the non-aqueous solvent contains a cyclic carbonate and an acyclic carbonate as main components and contains 0.1 wt % or more and 4 wt % or less of 1,3-propane sultone and/or 1,4-butane sultone.
Patent Literature 6 discloses, as an invention intended to suppress capacity degradation occurred together with the progress of charge and discharge cycles, an electrolyte solution for lithium secondary batteries including a lithium salt as a solute, a specific cyclic organosulfate, and an organic solvent that dissolves the lithium salt, wherein the cyclic organosulfate is contained at a concentration of 0.1 to 50 wt % in the electrolyte solution.
Patent Literature 7 discloses, as an invention intended to improve the discharge characteristics at low temperatures, a non-aqueous electrolyte secondary battery including, in a non-aqueous electrolyte, at least one specific vinylene carbonate derivative at a concentration of 1 wt % or less and at least one specific glycol sulfate derivative at a concentration of 2 wt % or less.
Patent Literature 8 discloses, as an invention intended to suppress a decrease in capacity in a high-temperature environment and in a low-temperature environment and to suppress an increase in thickness of a battery in a high-temperature environment, a non-aqueous electrolyte battery including a positive electrode that contains a positive electrode active material capable of occluding and releasing lithium ions, a negative electrode that contains a negative electrode active material capable of occluding and releasing lithium ions, and a non-aqueous electrolyte, wherein the non-aqueous electrolyte contains one or more cyclic organosulfate derivatives and one or more fluorinated ether compounds.